Apparatus for drilling deflecting well bores



Mwah M, 95@ J. A. ZUBLIN 2,5@6

APPARATUS FOR DRILLING DEFLECTING WELL BoREs Fired March 26, 1945 y muli ff Patented Mar. 14, 195@ attain UNlTED STATES PATENT OFFICE APPARATUS FOR DRILLING DEFLECTING WELL EURES This invention relates to an improved apparatus for drilling an oriented delecting bore from an existing well bore, and which is accurate in its desired azimuth and its angle of deection.

It is often desired to drill from the bottom of an existing well bore an extension thereof deflecting from the direction of the existing bore in a predetermined oriented direction. This has been done through the use of whipstocks, knuckle joints, and other types of auxiliary tools, designed to guide the drill bit at the correct angle of deection. However, these devices have been used with rotating drill pipe and have presented problems for the reason that the rotating pipe will not maintain the desired azimuth.

In my prior Patent No. 2,336,336, there is disclosed a rotary turbine bit of the type which makes the rotation oi a drill pipe unnecessary.

It is the purpose of the present invention to provide apparatus for accurately drilling a deflecting bore from the bottom of an existing bore through the medium of a non-rotating drill stem and a rotating turbine bit.

In some instances, it is desirable to initiate a deflecting bore from an existing well at an inter- -f mediate level thereof. This may be conveniently done by lling the existing well bore to the desired intermediate level with a suitable ller such as liquid cement which, when hardened, forms a new or articial well bottom suliciently rm to serve as a starting point for the deflecting drilling operation. In this application therefore the term bottom of an existing well refers to either the natural bottom or to any artificial bottom formed by lling the well bore to a desired intermediate level.

The prior art practices in drilling deiiecting bores from an existing well bore have entailed the initial drilling of a smaller bore than the existing well bore for the reason that all deecting devices need space for operation. The smaller bore thus drilled is subsequently reamed to produce a bore of larger size.

|These practices have also been characterized by the circumstance that the drilling of the small deecting bore is initiated at one side of the existing well bore, leaving a substantial shoulder which makes casing of the deecting bore diflicult if not impossible. It is a further object and advantage of the present invention to overcome this diiliculty.

It is a specific object of the invention to permit of the initiation oi the drilling of a deecting bore from a point at the approximate center of the existing bore whether the existingvbore be vertical or already disposed at an angle to the vertical. The invention will be further described in connection with the accompanying drawings, in which:

Fig. 1 illustrates the present invention applied to a vertical existing well bore;

Fig. 2 illustrates a modified form of the invention adapted for application to an existing well bore extending at an angle to the vertical;

Fig. 3 illustrates the progression of the drilling of the deflecting bore initiated as indicated in Fig. 2; and

Fig. i is a top plan view of the centering guide illustrated in Figs. 2 and 3.

Referring to Fig. 1, the existing vertical well bore is indicated at I1, and has the center line indicated at i8. well the drill string I9 carrying the lower permanently bent section 2l) coupled to the drill string l 9 at 2l. The permanently bent drill stem section 20 carries at its lower end a turbine driven drill bit 22 such, for example, as illustrated in my Patent No. 2,336,336. v

The drill stem section 2D is bent to a predetermined degree to provide the requisite angle of deection. The direction in which the deflecting bore is to be drilled is controlled by orienting the permanently bent drill stem section 2l) and the bit 22 from the surface of the well. The drill string is connected at its upper end with a square or hexagonal drill stem, which fits into a bushing of a rotary table. Since this structure is conventional, it is not shown. After the drill string has been properly oriented in the existing well bore, it assumes a denite orientation within the rotary table. The table is then looked in this position, and from that point on the square drill stem can beraised and lowered freely without disturbing the orientation of the bent drill stem section 2li and the turbine bit 22 within the well.

When the lower inclined portion 23 of the bent drill section 2i) is oriented so that it extends in the desired direction of dellection, the drill string i9 is therefore locked at the surface of the well against rotation. It will be observed that the arrangement is such as to permit initiation of vthe drilling of the deflecting bore at a point approximating the' center 2liA of the bottom 25 of the existing well bore Il. When the drill string i9 is held against rotation with the permanently bent drill stem 2l] oriented as indicated in Fig. -1, drilling of the deflecting bore through rotation of-the turbine bit 22 and the advancing of the same results in the production of a deflecting bore taking the direction indicated by the dotted There is introduced into the lines 2B. When this small diameter deecting bore is subsequently reamed, a bore is produced as indicated by dotted lines 2l which joins the existing vertical bore I1 with no abrupt shoulder or obstructions, and therefore the deflecting extension of the existing bore can be readily cased.

It will be appreciated that the turbine bit 22 will take a direction conforming to that of the inclined portion 23 oi the permanently bent drill stem 2G. The degree of deflection will, therefore, be determined by the extent to which the drill stem section 2t is bent. Different degrees of deflection may be obtained byusing different-drill stem sections immediately back of the turbine' driven bit 22. It will be appreciated that thc present invention is concerned primarily with the drilling of delecting bores witha relatively-small angle of deflection and is not intended for the drilling of abruptly deviating bores extending laterally from the existing Well.

In Fig. 2, the invention is illustrated as being applied to a well in which the bore 25.having a center line 29 already extends at a substantial angle to the Vertical. This situation is not infrequently encountered in the drilling of oil Wells because of deflection of the drill bit by changes in the formation. When this occurs, it is highly desirable to restore the bore to its original direction, and this can be accomplished in accordance with the present invention by providing a centering guide 3D having a sleeve 3l adapted to nt reasonably loosely about the permanently bent drill section 2li. The centering guide Sii embraces a series of spaced ribs 32 as more particularly shown in Fig. 4. The diameter of the centering: guide 3D, including the ribs 32, corresponds fairly closely to the diameter of the existing well bore 23.

Fig. 5 is a View par ly in section and partly in side elevation of a turbine driven bit suitable for use in practicing `the invention.

The centering guide Sil is adapted to be interlocked to theshank of the turbine bit 22 by means of a frangible pin 33. In this way, permanently bent drill stem section 2U, carrying the turbine bit 22, can be lowered into the existing bore 28 and the drill bit 22 oriented in close juxtaposition to the center of the bottom of the well bore 28 and with the inclined portion 23 of the bent drill stem section 2t extending in the desired direction. When so oriented, the drill string I9 is locked against further rotation, the turbine driven bit 22`is rotated and advanced into the formation. The result will be the drilling of a short section of new hole, indicated generally at X, during which time the centering guide Sil moves to the bottom of the hole.

When the centering guide si! reaches the bottom of the existing well bore, the frangiblepin 33 is sheared, and the bent drill stem section 2li permitted to progress through the sleeve 3i. As the bit 22 progresses, it will be guided by the angular portion 23 of the permanently bent drill stem section 2) to produce a deflecting bore as indicated by the dotted` lines Si?, Fig. 2, and as shown in full lines 35, Fig. 3.

While the centering guide 32 may-be'employed in an'undeflecting vertical bore such as li oi Fig. l, it is not required in such a vertical bore, but it is essential in the drilling of an oriented deectingn bore from an existing bore that already extends at an angle to the vertical, since otherwise theV bit 22 would hug one side or" the existing bore and the deflecting bore would be initiated in an objectionable manner.

The turbine drive for the bitA 22 may be oi Iany conventional type. The illustrative type shown in Fig. 5 includes a passage 36 for the mud laden duid. Stationary vanes 31 impart a whirling action to this fluid which then impinges on the vanes 38 which are formed in the shank of the bit 22. The bit 22 is thus caused to rotate relative to the drill pipe as will be apparent from an inspection of Fig. 5.

From the foregoing, it will be apparent that the present method embraces the provision-of a permanently bent drill stem section bent at the desired angle of deilection for the deiiecting bore to be'drilled', the orientation of the bit and permanently bent drill stem section so as to initiate the drilling of a denecting bore from a point juxtaposed to the center of the bottom of the existing bore, the holding of the permanently bent drill stem section against rotation while rotating and advancing the turbine bit to thus effect the desired drilling action. This method is very effective. `It is far more advantageous than methods involving the use of whip" stocks and other expediente employed in connection with rotating drill stems.

It will be appreciated thatthelinear extent of the permanently bent drill stem section may be varied so as to provide. variations in the degree of angularity of the deiecting bore to be produced.

Having thus described my invention, what I cla-im is:

l. Apparatus for drilling a deectingextension from the bottom of an existing` well bore starting at a point substantiallyl co-axial with the existing bore, comprising a drill stem.- rotatably carrying a rotary bit at its lower end, said drill steml embracing a section in juxtaposition to said bit permanently bent intermediate its; ends to provide a lcwei` section extending at an angle to the axis ci the, existing bore such that whenthe btis seated f at substantially the center ofthe bottom of the existing. bore said lower section of the drilll stem extends upwardly from# the; bit at the angle ci deilection desired for the-extensionpto be drilled and guideA means carried by said drill stem adapted to insure'seating of saidbit at the approximate centerv of the bottom of the existing bore.

2. Apparatus for drilling a. deecting extension from an existing well bore starting from a point substantially at the center of the bottom of the existing bore comprising a drill string rotatably carrying a drivenv rotary bit at its lower end, said drill string including a permanently bent section in juxtaposition to the bit, the extent and location of the bend being such as to provide a drill stem section immediately behind the bit extending therefrom at the predetermined ang-le of the desired deflecting bore when said 4bit is seated at approximately the center of the bottom of the existing well bore, and guide means carried by said drill stem adapted to insure seating of said bit at the approximate center of thev bottom of the existing bore.

3. Apparatus for drillingv a deecting extension from an existing well bore starting from a point substantially at the center of the bottom of the existing bore, comprising a drill string with its lowest section permanently bent intermediate its ends, a power driven rotary bit rotatably connected to the free end of said permanently bent section, guide means carried by said bit and permanently bent section adapted to ensure setting of said bit substantially 'in the center of the bottom of the existing Well bore before starting the drilling of the deflectingbore, and also adapted 5 6 topermit movement of said bent section therethrough to hold said bit and bent section in the UNITED STATES PATENTS desired deected position during the drilling of Number Name Date said defiecting extension. 1 2,167,194 Anderson July 25, 1939 JOHN A. ZUBLIN. g, 2,327,693 Armentrout Aug. 24, 1943 2,336,336 Zubln Dec. 7, 1943 REFERENCES CITED 2,336,338 Zublin Dec. 7, 1943 2,344,277 Zublin Mar. 14, 1944 The following references are of record in the me of this patent: 2,332,933 Zublln Aug. 14, 1945 

